It's one of the trickiest aspects of sports car engineering: The things you do to improve grip on dry pavement often reduce a car's traction in wet weather. A lightweight chassis and wide tires with minimal tread can all increase a car's tendency to hydroplane. That's a huge problem for buyers, who might not expect their fast, grippy, surefooted performance vehicles to be so compromised by damp pavement.
Porsche has a potential solution that's coming to the 992-generation 2020 911, and it involves having the car listen for the sound of wet pavement.
We've briefly explained this system before, and spoken with the engineers who designed and implemented it, but it's worth a closer look on its own. Sensors tucked into the front wheel wells analyze the intensity of the sound of water being splashed up by the tires. Think of the sensors as something between a conventional microphone and a parking sensor. By inferring the amount of water on the road, and comparing that information with vehicle speed, the car can decide to suggest that the driver engage "Wet Mode."
"We found out during pre-development investigations that the noise of the road and the surface causes different frequencies in the wheelhouse," August Achleitner, chief engineer for the new 911, told us in November 2018. "We can detect very well how much water is on the road."
When selected, Wet Mode softens throttle response, keeps automatic-transmission-equipped vehicles in a higher gear, reduces engine torque and limited-slip differential lockup, and makes the stability control and ABS more sensitive. All-wheel drive models will send more torque to the (narrower) front tires, and the new, wider spoiler will deploy to increase rear-axle downforce.
Of course, the 911 will still allow drivers to turn off Wet Mode and deactivate stability and traction control in pursuit of the kind of wet-pavement sliding antics you see at the top of this page. The 911 is still a sports car, even if it's been given new tools to help save youfrom oversteer on your daily commute.